Conventionally, an automated apparatus such as so-called industrial robot and NC (Numerical Control) machine tool has been introduced in various industrial fields. The introduction of this apparatus allows enhancement of production efficiency.
This apparatus has a movable unit such as an arm for gripping a work and an end mill for shaping the work. This movable unit is movable by a plurality of drive shafts, and these drive shafts are driven by a servomotor or a stepping motor.
When this apparatus is used to shape the work, for example, a behavior thereof must be determined. As a method for determining the behavior, there are an off-line calculation scheme in which the behavior is calculated in advance, and an on-line calculation scheme in which the behavior is dynamically calculated during operation.
There have been proposed various techniques as a conventional technique for controlling the behavior of the apparatus. For example, according to a numerical controller disclosed in Japanese Patent Laying-Open No. 07-064620 (PTL 1), high-speed and high-accuracy velocity control in consideration of acceleration/deceleration control is possible, smooth driving on a spline curve is possible, abnormal vibrations of a machine tool can be reduced, and whether a higher priority is given to velocity or accuracy can be selected. More specifically, in the numerical controller disclosed in PTL 1, by suppressing abrupt acceleration/deceleration at a start point and an end point, mechanical vibrations can be suppressed, and deceleration stop is possible at a specified acceleration (deceleration) and without going beyond a target position.
According to a curve interpolation acceleration/deceleration control method disclosed in Japanese Patent Laying-Open No. 2000-148223 (PTL 2), there are obtained smooth acceleration and deceleration for high-speed movement in accordance with the shape of a curve.
According to an intra-interpolation curve acceleration/deceleration processing method disclosed in Japanese Patent Laying-Open No. 2000-163114 (PTL 3), a machine can be moved along an instructed trajectory regardless of a curvature of a curve.
According to an NC machining method disclosed in Japanese Patent Laying-Open No. 06-075621 (PTL 4), by adding a new sampling point to only a portion having a large curvature, a curve is approximated with the minimum number of sampling points (data) and an original figure which is smooth and small in shape difference is reproduced.
According to a numerical controller disclosed in Japanese Patent Laying-Open No. 01-147610 (PTL 5), interpolation control is performed by spline interpolation control.
As for an apparatus placed in a production line for mass-producing products of the same kind, a set value (machining program) such as a target trajectory may be preset and the apparatus may be operated in accordance with this set value. However, in a multikind and small quantity production line for producing various products, setting such a set value (machining program) for each product is difficult in terms of cost and the like. Thus, there is a demand for reducing production cost, for example, by using the common machining program and dynamically setting the target trajectory and the like in accordance with commodity specifications and the like.